MODEL PREDICTIVE CONTROL OF AN AUV USING DE-COUPLED APPROACH

This paper considers the decoupled dynamics and control of an Autonomous Underwater Vehicle (AUV). The decoupled model consists of speed, steering and depth subsystems. Generally AUV model is unstable and nonlinear. The central theme of this paper is the development of model predictive control (MPC) for underwater robotic vehicle for ocean survey applications. The proposed MPC for decoupled structure can have simple implementation. Simulation results have been presented which confirm satisfactory performance. Decoupled approach is well suitable for applying control.

Approaching an Efficient and Feasible Carnot Engine by Carnot Cycle Analysis

Based on the knowledge exhibited in the literature on the Carnot cycle, a preliminary study is carried out on Carnot machines capable of implementing the Carnot cycle at high thermal efficiency. Therefore, two engine structures are proposed: (i) reciprocating single and double-acting cylinder-based thermal engines implemented under a closed processes-based Carnot thermal cycle characterised by a mechanical structure internally coupled, and (ii) similar engines characterised by a mechanical structure internally decoupled. In order to perform the cycle analysis, however, observational (experimental) evidence confirms on a daily basis the fact that there are two performance criteria: conventional (output net work/input heat) thermal efficiency and output/input energetic-based first law efficiency. Based on such premises, this study investigates both coupled and decoupled Carnot engine structures. The results confirm that an important fraction of heat can be converted into useful work by configuring a decoupled structure of the Carnot engine. Indicative results support the use of internally decoupled thermal machines, especially when the heat source has a low or medium temperature. Even at high temperatures, such machines are advantageous in terms of energy efficiency. Furthermore, avoiding internal coupling allows for power regulation without disturbing interactions due to variations in load, thus enabling robust control.

Proposal of a Decoupled Structure of Fuzzy-PID Controllers Applied to the Position Control in a Planar CDPR

The design of robot systems controlled by cables can be relatively difficult when it is approached from the mathematical model of the mechanism, considering that its approach involves non-linearities associated with different components, such as cables and pulleys. In this work, a simple and practical decoupled control structure proposal that requires practically no mathematical analysis was developed for the position control of a planar cable-driven parallel robot (CDPR). This structure was implemented using non-linear fuzzy PID and classic PID controllers, allowing performance comparisons to be established. For the development of this research, first the structure of the control system was proposed, based on an analysis of the cables involved in the movement of the end-effector (EE) of the robot when they act independently for each axis. Then a tuning of rules was carried out for fuzzy PID controllers, and Ziegler–Nichols tuning was applied to classic PID controllers. Finally, simulations were performed in MATLAB with the Simulink and Simscape tools. The results obtained allowed us to observe the effectiveness of the proposed structure, with noticeably better performance obtained from the fuzzy PID controllers.

Model Predictive Control of an AUV Using De-Coupled Approach

This paper considers the decoupled dynamics and control of an Autonomous Underwater Vehicle (AUV). The decoupled model consists of speed, steering and depth subsystems. Generally AUV model is unstable and nonlinear. The central theme of this paper is the development of model predictive control (MPC) for underwater robotic vehicle for ocean survey applications. The proposed MPC for decoupled structure can have simple implementation. Simulation results have been presented which confirm satisfactory performance. Decoupled approach is well suitable for applying control.

Marine boundary layer structure as observed by space-based Lidar

The marine boundary layer (MBL) structure is important to the exchange of heat, momentum, and moisture between oceans and the low atmosphere and to the marine low cloud processes. This paper explores MBL structure over the eastern Pacific region with a new 4 year satellite-based dataset. The MBL aerosol lidar backscattering from the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) was used to identify the MBL top (BLH) and the mixing layer height (MLH). Results showed that MBL is generally decoupled with MLH / BLH ratio ranging from ∼ 0.5 to ∼ 0.8 and the MBL decoupling magnitude is mainly controlled by estimated inversion strength (EIS) that affects the cloud top entrainment process. The systematic differences between drizzling and non-drizzling stratocumulus tops, which may relate to the meso-scale circulations or gravity wave in MBL, also show dependence on EIS. Further analysis indicated that the MBL shows similar decoupled structure for clear sky and cumulus cloud-topped conditions, but is better mixed under stratiform cloud breakup and overcast conditions.